equivalence VS implication

[slovac]

Could you please tell me whether I am right about the following statements?

A. Someone watches El Clasico EQ Someone watches Real Madrid VS Barcelona.
my answer: CORRECT (El Clasico means that the match is between RM and B - there is not other option)

B. Someone watches Real Madrid VS Barcelona. EQ Someone watches El Clasico
my answer: CORRECT

C. Someone watches El Clasico IMPLICATION Someone watches Real Madrid VS Barcelona.
my answer: INCORRECT (Because I did not highlight that there is no other option)

D. Someone watches Real Madrid VS Barcelona. IMPLICATION Someone watches El Clasico
my answer: INCORRECT

E. Someone watches the match between West Ham United and Chelsea London IMPLICATION Someone watches a London derby.
my answer: CORRECT (There are other matches which are labelled as London derby: Tottenham vs Chelsea, Fulhan vs Arsenal...)

F. Someone watches the match between West Ham United and Chelsea London EQ Someone watches a London derby.
my answer: INCORRECT (Because there are more than one London derby)

G. Someone watches a London derby IMPLICATION Someone watches the match between West Ham United and Chelsea London.
my answer: INCORRECT (Because there are other London derbies)

Thank you

 

[stapel]

Could you please tell me whether I am right about the following statements?

I don't know anything about futbol, so I don't know the names, etc. I've referenced what I found elsewhere online.

A. Someone watches El Clasico EQ Someone watches Real Madrid VS Barcelona.
my answer: CORRECT (El Clasico means that the match is between RM and B - there is not other option)

You are correct regarding the definition of an "El Clásico" game, so the two statements must mean the same thing. They are equivalent.

B. Someone watches Real Madrid VS Barcelona. EQ Someone watches El Clasico
my answer: CORRECT

This is the same as the previous statement, but with the statements swapped. It's still true, because there is no ordering for "equals".

C. Someone watches El Clasico IMPLICATION Someone watches Real Madrid VS Barcelona.
my answer: INCORRECT (Because I did not highlight that there is no other option)

If someone is watching an "El Clásico" game, what other teams could he be watching? Mustn't he be watching the only two teams who ever (by definition) play in such a game?

D. Someone watches Real Madrid VS Barcelona. IMPLICATION Someone watches El Clasico
my answer: INCORRECT

Same question as for (C).

E. Someone watches the match between West Ham United and Chelsea London IMPLICATION Someone watches a London derby.
my answer: CORRECT (There are other matches which are labelled as London derby: Tottenham vs Chelsea, Fulhan vs Arsenal...)

A "London derby" can be a game between any two of a number of teams. The two listed teams are among those whose matches are "London derbies". So the implication is correct.

F. Someone watches the match between West Ham United and Chelsea London EQ Someone watches a London derby.
my answer: INCORRECT (Because there are more than one London derby)

This is an "equals", which implies that a "London derby" is a game ONLY between these two teams. Since, as you've noted, other teams are included in the listing, the statements are not equivalent.

G. Someone watches a London derby IMPLICATION Someone watches the match between West Ham United and Chelsea London.
my answer: INCORRECT (Because there are other London derbies)

Your answer is correct.

 

[slovac]

Thank you. Does it mean that I was right about each statement except of these two (C and D)?:

C. Someone watches El Clasico IMPLICATION Someone watches Real Madrid VS Barcelona.
my answer: INCORRECT (Because I did not highlight that there is no other option) - CORRECT IS THE RIGHT ANSWER



If someone is watching an "El Clásico" game, what other teams could he be watching? Mustn't he be watching the only two teams who ever (by definition) play in such a game?

Originally Posted by slovac
D. Someone watches Real Madrid VS Barcelona. IMPLICATION Someone watches El Clasico
my answer: INCORRECT - CORRECT IS THE RIGHT ANSWER



Same question as for (C).

 

[Ishuda]

When I was taking logic, I found it much easier to use the words valid and invalid rather than correct and incorrect. One of the big reasons for this was the implication and something I initially has a hard time wrapping my mind around. ANY implication statement which is not a "if True then False (True implies False)" is valid. Thus, as staple said, C and D are valid implications since they are "If True then True" statements.

The reason I had a problem with this initially is that "If the sun had disappeared yesterday we would all be more brilliant today" (False implies anything) is a valid statement. I finally accepted the ideal though and started hoping the sun would go out so I could be more brilliant tomorrow until someone pointed out that although the statement was valid, it was not necessarily true.